commit 2d74793fb42a725dc29dcd4b9ec286ebee8cdbe1
Author: Sylvain Munaut <s.munaut@whatever-company.com>
Date:   Thu Jun 5 11:28:27 2014 +0200

    rgw: Don't send error body when it's a HEAD request
    
    The main 'operation' know not to send any body for HEAD requests.
    
    However for errors, this was not the case, the formatter would be
    flushed and would send the error 'message' in the body in all cases.
    
    For the FastCGI case it doesn't seem to be an issue, it's possible
    that the webserver (apache/lighttpd/...) cleans up the response
    into shape.
    
    But when using the new civetweb frontend this cause invalid HTTP.
    
    Fixes #8539
    
    Signed-off-by: Sylvain Munaut <s.munaut@whatever-company.com>

diff --git a/src/rgw/rgw_rest.cc b/src/rgw/rgw_rest.cc
index 69948a6..b74002d 100644
--- a/src/rgw/rgw_rest.cc
+++ b/src/rgw/rgw_rest.cc
@@ -180,7 +180,7 @@ void rgw_flush_formatter_and_reset(struct req_state *s, Formatter *formatter)
   std::ostringstream oss;
   formatter->flush(oss);
   std::string outs(oss.str());
-  if (!outs.empty()) {
+  if (!outs.empty() && s->op != OP_HEAD) {
     s->cio->write(outs.c_str(), outs.size());
   }
 
@@ -192,7 +192,7 @@ void rgw_flush_formatter(struct req_state *s, Formatter *formatter)
   std::ostringstream oss;
   formatter->flush(oss);
   std::string outs(oss.str());
-  if (!outs.empty()) {
+  if (!outs.empty() && s->op != OP_HEAD) {
     s->cio->write(outs.c_str(), outs.size());
   }
 }